A robot (traveling apparatus) disclosed in Patent Document 1 includes a pair of crawler devices extending in a front-rear direction of a body disposed on the left and right of the body. Each of the crawler devices includes front and rear wheels and a belt (endless elongated member) wrapped around the wheels.
The robot having the features mentioned above can be moved forward or backward by rotationally driving the left and right crawler devices in the same direction at the same speed. The robot can make a turn to the left or right drawing a curve by rotationally driving the left and right crawler devices at different speeds. Moreover, the robot can make a pivot turn (turning in place without moving) by rotationally driving the left and right crawler devices in different directions.
The robot cannot change directions by pivot turning at a corner of a narrow passage curving at a right angle. The robot cannot change directions by pivot turning on an uneven ground either because a resistance of the ground interferes with rotational driving of the crawler devices.
Moreover, in a case where a destination is in an oblique direction, the robot may not be able to be moved linearly to the destination, and therefore may not be able to reach the destination accurately.
Patent Document 2 discloses a robot that can be moved in two directions and that can solve the problems mentioned above. The robot includes a pair of crawler devices extending in a first direction and spaced from each other in a second direction orthogonal to the first direction. Each of the crawler devices includes a crawler unit rotatable about a rotational axis extending in the first direction. The crawler unit includes a support extending in the first direction and a pair of crawler structures mounted to the support and opposed to each other with the rotational axis extending therebetween.
The robot of Patent Document 2 can be moved in the first direction by driving the crawler structures of the pair of crawler units. A mode of moving in this manner is referred to as “crawler moving” hereinafter.
The robot can be moved in the second direction by the pair of crawler units being rotated about the rotational axes and rolling in the second direction. A mode of moving in this manner is referred to as “moving by rolling” hereinafter.
The robot of Patent Document 2 can change directions of movement from the first direction to the second direction and from the second direction to the first direction not by pivot turning but by selecting between the crawler moving and the moving by rolling. Moreover, the robot can be moved linearly in any oblique direction by performing the crawler moving and the moving by rolling at the same time. A mode of moving in this manner is referred to as “oblique moving” hereinafter.